RESUMEN
Diabetic neuropathy (DN) is one of the principal complications of diabetes mellitus (DM). Dorsal root ganglion (DRG) neurons are the primary sensory neurons that transduce mechanical, chemical, thermal, and pain stimuli. Diabetes-caused sensitivity alterations and presence of pain are due to cellular damage originated by persistent hyperglycemia, microvascular insufficiency, and oxidative and nitrosative stress. However, the underlying mechanisms have not been fully clarified. The present work addresses this problem by hypothesizing that sensitivity changes in DN result from mechanotransduction-system alterations in sensory neurons; especially, plasma membrane affectations. This hypothesis is tackled by means of elastic-deformation experiments performed on DGR neurons from a murine model for type-1 DM, as well a mathematical model of the cell mechanical structure. The obtained results suggest that the plasma-membrane fluidity of DRG sensory neurons is modified by the induction of DM, and that this alteration may correlate with changes in the cell calcium transient that results from mechanical stimuli.
Asunto(s)
Diabetes Mellitus Experimental , Neuropatías Diabéticas , Animales , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/metabolismo , Neuropatías Diabéticas/complicaciones , Ganglios Espinales/metabolismo , Mecanotransducción Celular , Ratones , Dolor/complicaciones , Dolor/metabolismo , Ratas , Ratas Sprague-Dawley , Células Receptoras Sensoriales/metabolismoRESUMEN
Noise is present in nature, and it affects the nervous and cardiovascular system. Noise added to stimuli may change the performance of excitable cells. In this paper, we study the effect of noise on the two main heart cell types: pacemaker and myocardial cells. This study investigates whether noise can induce changes in calcium dynamics on the two main heart cell types: pacemaker and myocardial cells, when stimuli with periodic electrical signals are disturbed by Gaussian white noise. Calcium dynamic parameters were obtained using imaging signals. Our results show that low intensities of noise favor amplitude and raise rate calcium dynamics, although our results show that the pacemaker cells are not affected by a noisy stimulus. Altogether, these findings suggest that noise plays a key role in calcium dynamics.
Asunto(s)
Calcio/metabolismo , Miocitos Cardíacos/metabolismo , Animales , Señalización del Calcio , Línea Celular , Embrión de Pollo , RatasRESUMEN
The mechanosensitivity of cells depends on the lipid-protein interactions of the plasma membrane. Affectations in the lipid region of the plasma membrane affect the transduction of mechanical forces, and any molecule that modifies the biophysical integrity of the lipid bilayer can alter the mechanical activity of the proteins inside the membrane. To understand whether inhibitors of mechanically activated ion channels affect the mechanical properties of the plasma membrane, we evaluated the rigidity of the membrane of sensory neurons of the DRG of mice using a variant of the scanning ion conductance microscopy method, which allows us to calculate the Young's modulus of individual cells before and after the perfusion of different doses of Gd3+, ruthenium red and GsMTx-4. Our results suggest that these molecules compromise the membrane by increasing the Young's modulus value, which indicates that the membrane becomes more rigid; these compounds act through different mechanisms and by a non-specific manner, each one shows a certain preference for specific cell subpopulations, depending on their cell size and their reactivity to isolectin B4. Our results support the idea that the biophysical properties that result from the interactions that arise in the membranes are part of the mechanotransduction process.
Asunto(s)
Membrana Celular/metabolismo , Moduladores del Transporte de Membrana/metabolismo , Células Receptoras Sensoriales/metabolismo , Células Receptoras Sensoriales/ultraestructura , Animales , Cadmio/metabolismo , Línea Celular , Células Cultivadas , Módulo de Elasticidad , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Masculino , Mecanotransducción Celular , Ratones , Rojo de Rutenio/metabolismo , Transducción de Señal , Venenos de Araña/metabolismoRESUMEN
During capacitation of mammalian sperm intracellular [Ca(2+)] and cyclic nucleotides increase, suggesting that CNG channels play a role in the physiology of sperm. Here we study the effect of capacitation, 8Br-cAMP (8-bromoadenosine 3',5'-cyclic monophosphate) and 8Br-cGMP (8-bromoguanosine 3',5'-cyclic monophosphate) on the macroscopic ionic currents of mouse sperm, finding the existence of different populations of sperm, in terms of the recorded current and its response to cyclic nucleotides. Our results show that capacitation and cyclic nucleotides increase the ionic current, having a differential sensitivity to cGMP (cyclic guanosine monophosphate) and cAMP (cyclic adenosine monophosphate). Using a specific inhibitor we determine the contribution of CNG channels to macroscopic current and capacitation.
Asunto(s)
GMP Cíclico/fisiología , Canales Catiónicos Regulados por Nucleótidos Cíclicos/fisiología , Capacitación Espermática , 8-Bromo Monofosfato de Adenosina Cíclica/análogos & derivados , 8-Bromo Monofosfato de Adenosina Cíclica/farmacología , Animales , AMP Cíclico/farmacología , GMP Cíclico/análogos & derivados , GMP Cíclico/metabolismo , GMP Cíclico/farmacología , Canales Catiónicos Regulados por Nucleótidos Cíclicos/agonistas , Canales Catiónicos Regulados por Nucleótidos Cíclicos/antagonistas & inhibidores , Canales Catiónicos Regulados por Nucleótidos Cíclicos/metabolismo , Relación Dosis-Respuesta a Droga , Resistencia a Medicamentos/efectos de los fármacos , Masculino , Potenciales de la Membrana/efectos de los fármacos , Ratones , Capacitación Espermática/efectos de los fármacos , Capacitación Espermática/fisiología , Espermatozoides/efectos de los fármacos , Espermatozoides/fisiologíaRESUMEN
Cannabinoid receptor 2 (CB2) agonists provide the potential for treating chronic pain states without CNS effects associated with CB1 receptor activation. Animal models suggest that they act mainly via non-neuronal cells, possibly inhibition of inflammatory cells in the periphery or CNS, or via release of beta-endorphin; however, the clinical relevance and mechanism of analgesic action is uncertain. Here, we demonstrate colocalisation of CB2 with CB1 and the capsaicin receptor TRPV1 in human dorsal root ganglion (DRG) sensory neurons and increased levels of CB2 receptors in human peripheral nerves after injury, particularly painful neuromas. In primary cultures of human DRG neurons, selective CB2 agonists blocked activation of inward cation currents and elevation of cytoplasmic Ca2+ in response to capsaicin. These inhibitory effects were reversed by GW818646X a CB2 antagonist, and 8-bromo cAMP, but not by SR141716 a CB1 antagonist, or naloxone. Thus CB2 receptor agonists functionally inhibited nociceptive signalling in human primary sensory neurons via a mechanism shared with opioids, of adenylyl cyclase inhibition, but not via mu-opioid receptors. We conclude that CB2 agonists deserve imminent clinical trials for nociceptive, inflammatory and neuropathic chronic pain, in which capsaicin or heat-activated responses via TRPV1 may provide a clinical marker.
Asunto(s)
Capsaicina/antagonistas & inhibidores , Capsaicina/farmacología , Receptor Cannabinoide CB2/agonistas , Receptor Cannabinoide CB2/análisis , Células Receptoras Sensoriales/química , Adolescente , Adulto , Anciano , Animales , Células CHO , Cannabinoides/farmacología , Células Cultivadas , Niño , Cricetinae , Cricetulus , Femenino , Humanos , Masculino , Persona de Mediana Edad , Inhibición Neural/efectos de los fármacos , Inhibición Neural/fisiología , Receptor Cannabinoide CB2/antagonistas & inhibidores , Células Receptoras Sensoriales/efectos de los fármacosRESUMEN
Capsaicin (Cap) and its analogs (CAPanalogs) have diverse effects in sensory neurons including analgesia, implying they modulate other cellular targets besides the TRPV1 Cap receptor. Since Cap and CAPanalogs are not largely available and their chemical synthesis is cumbersome, they have been obtained through a direct lipase-catalyzed reaction. Capsiate, the ester CAPanalog, was synthesized using a novel enzymatic transacylation one-pot strategy. Five different CAPanalogs were synthesized by amidation in 2-methyl-2-butanol with higher yields than previously reported. Voltage-dependent Ca(2+) channels (Ca(v)s) are among the main Ca(2+) entry paths into cells. They are classified as high-voltage-activated Ca(2+) channels (HVA) and low-voltage-activated Ca(2+) channels (LVA) constituted only by T-type channels. Though HVA Ca(v)s are Cap sensitive, it is not known if capsaicinoids inhibit LVA Ca(v)s which participate in the primary sensory neuron pain pathway. Here we first report that Cap, dihydrocapsaicin, N-VAMC(8), N-VAMC(9), and N-VAMC(10) can directly and partially reversibly inhibit T-type Ca(v)s, whereas olvanil, capsiate, and vanillylamine cannot. The Cap inhibition of T-type Ca(v)s was independent of TRPV1 activation.